The seabed comeback: decade-long trawling ban sparks hidden marine life boom

After nearly a decade of protection from bottom trawling and dredging, scientists have recorded a marked resurgence of marine life in a Scottish protected area –  evidence, they say, of what is being lost elsewhere.

Muddy seabeds, long dismissed as barren, are proving to be anything but. When protected, life recovers rapidly, scientists say.

A decade of protection delivers measurable gains

Research led by Dr Ben Harris at the University of Exeter focused on the South Arran Marine Protected Area. The results show that nearly ten years without bottom-trawling has significantly boosted biodiversity. The study, conducted under the Convex Seascape Survey, a global research programme involving Blue Marine Foundation, the University of Exeter and Convex Group, offers one of the clearest pictures yet of recovery in action.

“These seabeds may appear empty, but they are anything but,” says Harris. “They can recover when protected, but much more slowly than fish communities in protected areas. That means long-standing, well-enforced protection is needed to realise their full ecological and biodiversity benefits.”

In a recently released paper –  Disentangling effects of protection on seabed organic carbon and biodiversity in a rare highly protected mud-dominated MPA –  its authors argue that highly protected zones now host about twice as many species as nearby fished areas, alongside far greater overall abundance. Seabed habitats free from trawling also host around three times as many individual animals living within the mud compared with exposed sites, showing greater abundance in protected areas. Worms, shellfish and other small but essential organisms –  the foundation of the marine food chain –  are returning in force.

Why long-term enforcement matters

The Arran study overturns the assumption that muddy seabeds are lifeless. In protected areas, scientists found thriving communities of worms, shellfish and other invertebrates – species that play a critical role in maintaining healthy marine systems.

For centuries heavy fishing gear has been dragged across Europe’s seabed, flattening habitats and stripping away fragile ecosystems. But now the resurgence is unmistakable, and foundational to wider ecosystem recovery.

But the study issues a note of caution: while biodiversity rebounds relatively quickly, climate benefits will take far longer. Researchers say carbon storage gains may take decades, more akin to the slow regeneration of an old-growth forest than a quick ecological fix.

“These systems rebuild over time,” says Harris. “Different species return at different stages, and together they shape how carbon is stored in the seabed.”

Delaying protection, he warns, risks pushing those long-term benefits even further out of reach.

Implications for marine policy and protection

The evidence adds weight to calls for stricter marine protections, particularly full bans on bottom trawling. The most robust recovery was observed in areas with the highest levels of protection, suggesting partial measures may fall short.

Across study sites, more than 1,500 species were recorded. Yet only a fraction of Europe’s seabed – 0.2 per cent – is currently protected from destructive fishing practices.